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Petit Jean Balloon Busting

Veetail88

Well Known Member
Without question, the most fun at Petty Jean this past weekend, in my humble opinion, was the balloon busting competition!

Having spent pretty much 100% of the 530 hours I have on my 8 doing everything I can to avoid hitting anything, suddenly that is exactly what the goal is and it was a blast!

Having busted 2 of the 3 balloons that were sent aloft for my killer pursuit like so many pheasants on a game farm, I?m quite certain that the one I missed was as solid a hit as the others.

So I posited that it may be possible for the target to pass through the propeller arc unscathed; and that I was actually perfect as far as the required skill goes. Oh Lord it?s hard to be humble!

While I was waiting on the end of the runway for my heat to begin, I had a great perspective of the target zone, and cranked the exposure rate on my $150 E-Bay special Lumix camera up to a dozen frames per second and burned a lot of images.

Here we have a sequence of our own Professor Horton as he launches his assault on an unwitting target balloon; and given the three images, It certainly appears this one went right through!

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So here?s the math. Flying at the targeted airspeed of 120 miles per hour, the forward speed equates to traveling at a rate of 2.112 inches for each 1/1000 of a second, or about 4.2 thousandths of a second for a 9? balloon to pass through the propeller disk.

In that same amount of time, a propeller turning at 2700 RPM will turn 69 degrees. (yes, please someone, check my math)

A 2 bladed prop, would cover 138 degrees, or only about 38% of the prop disc space, leaving the remaining 62% wide open.

I know this is imperfect as the balloon, being round, occupies different amounts of space at different times during the .0042 seconds it takes to pass through the disc, plus the prop has thickness, and the balloon might have been 11? in diameter, yada, yada, yada. But you get the picture.

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So I?m concluding that even if you skillfully maneuver your vehicle of destruction with the precision of a brain surgeon (who may or may not still have his brain surgery kit), that this is in the end, partially a game of chance.

None the less, the game is a BLAST! And kudos to the Petit Jean Indians for making it happen!

All ya?all should try your hand at it. You won?t be disappointed!
 
Interesting

Love those shots. Very interesting math/physics. In the second shot, comparing the size of the balloon to the wheel pant, it does appear to be right against the fuselage. For it to be that close to the fuse and still just a couple feet aft of the prop arc, it would seem that it MUST have passed through the arc unscathed!

Professor D. Horton! :)
 
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I could have given you empirical validation without the math. A former airpark neighbor had a duck put a 8" deep dent in the leading edge of his Debonair wing, inside the prop arc. No blood or damage on the prop.
 
I think the Petit Jean crew found a winner with this one.

Was a blast to watch, and next year I will participate!

-Dan
 
Placing bets.

To DanH,
Please tell Patti I no longer want the five dollars I bet on you back :)
Marvin
 
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Balloon is 9", speed is 2112 inches per second.

2700 RPM is 16200 degrees per second.

Thus (9 * 16200) / 2112 = 69 degrees during balloon passage.

Only 61 degrees if done at 2400.

Thank you Jesse. I feel soooo much better now.
 
Ah! I should have had my prop in full RPM. That way I wouldn?t have missed the 2nd and 3rd balloons.
 
I was the lucky dog that managed to score all three of the balloons. The third one was a surprise to me- I don?t recall hearing the pop like the first two, and it was the only one that I failed to smack head on with the spinner. Sounds like having a 3 blades prop does increase your odds of a kill after all. Since the balloon had to roll off of my spinner after contact, I?m sure the time spent in the kill zone had to go up as well.

Too bad I didn?t have my hat cam on for this. It was really neat to see the ballon shards get flung around the canopy!

Don
 
Balloon busting

I guess I will have to give it a try next year... I should have a better chance with my Three bladed prop 😜
 
Vlad, you might have the advantage here. Antonov showed a counter-rotating eight plus six on the AN-70 at the Paris Airshow....14 blades in one disc. A supersonic hummingbird wouldn't have a snowball's chance...

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Balloon is 9", speed is 2112 inches per second.

2700 RPM is 16200 degrees per second.

Thus (9 * 16200) / 2112 = 69 degrees during balloon passage.

Only 61 degrees if done at 2400.

Thank you Jesse. I feel soooo much better now.

Ah, but in the direction of motion, the balloon goes from 0" to 9" and back to 0" over a timespan of .00426 seconds, so you'd have to integrate the cross-section of the balloon perpendicular to the plane of rotation of the prop, wrt to t as t goes from 0 to .00426, and so forth :).
 
Balloon Pop

One can sure tell there's a little engineering and physics thread woven in the personality of RV pilots. I do wish someone had a camera so the rest of us could see this from the cockpit view.
 
I was the lucky dog that managed to score all three of the balloons. The third one was a surprise to me- I don?t recall hearing the pop like the first two, and it was the only one that I failed to smack head on with the spinner. Sounds like having a 3 blades prop does increase your odds of a kill after all. Since the balloon had to roll off of my spinner after contact, I?m sure the time spent in the kill zone had to go up as well.

Too bad I didn?t have my hat cam on for this. It was really neat to see the ballon shards get flung around the canopy!

Don

Don,
I know why you won: It was to get back at me. You offered to fly with me and be my spotter, but I said I wanted to try this solo. Well, you sure did show me, didn?t you? :cool:
That was some seriously nice flying, Don. 3 for 3...well done, Sir.
 
Ah, but in the direction of motion, the balloon goes from 0" to 9" and back to 0" over a timespan of .00426 seconds, so you'd have to integrate the cross-section of the balloon perpendicular to the plane of rotation of the prop, wrt to t as t goes from 0 to .00426, and so forth :).

Yeah, this was acknowledged. It actually gets worse as the propeller blade its self has varying thickness along with a twist and possibly a high pressure wave that might tend to push the balloon out of the way a bit and likely a dozen of so other effects that don't come immediately to mind. This was just a "close enough" exercise.
 
Not to diminish Dan's flying, but doesn't the cylinder of air flow through the prop have a significant constriction after the prop? Even if the balloon missed the prop tips, it would likely get sucked up against the fuselage after it passed the prop.
 
Integral Calculus

<SNIP>so you'd have to integrate the cross-section of the balloon perpendicular to the plane of rotation of the prop, wrt to t as t goes from 0 to .00426, and so forth :).

Ah, Calculus! Alas, it has been so long since I've burned the midnight oil enjoying your endless delights! ;)

I once woke up in the middle of the night, shouting, "d-y...d-x!" And then went back to sleep.

My wife thought I was nuts!!!
 
Not so fast ...Balloon Poppers ?? What about the 3ft streamer ???

Balloon is 9", speed is 2112 inches per second.

I think everyone on the ramp had a big time, betting on the almost dead eye aerial killers, while Homie Homsley announced the finer points of balloon missing to the tune of "10 Ways to Lose your Balloon" :D It was a hoot and it was even safe.... who'da thought? :rolleyes: BBUUUTTTTT.....

Let's get Dan to take another shot at the math. ;) First the balloon was a 12" balloon bought special because the 9" ones that come with the tanks were too small :rolleyes: Then to make it easier to see/hit, we added a 3 foot crepe paper streamer that doesn't really go through props very well but does stream backwards as the balloon follows the airflows immediately adjacent to the prop and flight surfaces (that's clost'by in Arkanese?.just saying;))

Having missed all three of mine, I am qualified to say that you can see the knot on the balloon go by at 130 MPH and the streamer is just a long red streak....but eagle eye AIRBOSS Bob was eyeball measuring them for cut off chunks and pops which oddly enough, you can clearly hear inside the airplane and on the ground ?.. or so I am told ?.

I checked with the rules committee ?. you knew we had one :) and they are now certainly willing to consider that you can you can push a 12"+ balloon with a three foot paper streamer though a prop and come out the other side without cutting something :rolleyes: but AirBoss Bob says he still isn't giving points for nothing but prop pops and streamers :--)

It was a blast ? See you back on the Mountain! :)

Bill

PS The rules were ?. fly the racetrack at 1600, 130MPH, initial 300 AGL over the numbers, and call for release,...do what you want but hit it in a climb, 1 point for a streamer and 4 points for a kill....thinking nothing but prop!

PPS ?. Don Winters was the deadeye dude of the day and he paid back right at 14 to 1 odds. I had $5 on his prop and got $70 back.... woo hoo! :D

PPPS ?. quick credit to Marvin Homsley for thinking we could do it and helping with the testing ?. which did not help him with the prop popping :)
 
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Let's get Dan to take another shot at the math. First the Balloon was a 12" balloon bought special because the 9" ones that come with the tanks were too small

Done, prop rotates 92 degrees for 12 inches, so about half the disc area is free pass.

Then to make it easier to see, we added a 3 foot crepe paper streamer (snip) eagle eye AIRBOSS Bob was eyeball measuring them for cut off chunks

I dunno about 'ole Eagle Eye. He scored me with three cut streamers, and Lord knows, I'll take all the help I can get....but the crepe paper looks suspiciously intact in Jesse's last photo.
 
:)
I dunno about 'ole Eagle Eye. He scored me with three cut streamers, and Lord knows, I'll take all the help I can get....but the crepe paper looks suspiciously intact in Jesse's last photo.

I think Bob said something about Horton Confetti but he is a gracious AirBoss :)

Ok so next year ?. 2 foot balloons. ;) We found a source for large amounts of helium.
 
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I think everyone on the ramp had a big time, betting on the almost dead eye aerial killers, while Homie Homsley announced the finer points of balloon missing to the tune of "10 Ways to Lose your Balloon" :D It was a hoot and it was even safe.... who'da thought? :rolleyes: BBUUUTTTTT.....

Let's get Dan to take another shot at the math. ;) First the balloon was a 12" balloon bought special because the 9" ones that come with the tanks were too small :rolleyes: Then to make it easier to see/hit, we added a 3 foot crepe paper streamer that doesn't really go through props very well but does stream backwards as the balloon follows the airflows immediately adjacent to the prop and flight surfaces (that's clost'by in Arkanese?.just saying;))

Having missed all three of mine, I am qualified to say that you can see the knot on the balloon go by at 130 MPH and the streamer is just a long red streak....but eagle eye AIRBOSS Bob was eyeball measuring them for cut off chunks and pops which oddly enough, you can clearly hear inside the airplane and on the ground ?.. or so I am told ?.

I checked with the rules committee ?. you knew we had one :) and they are now certainly willing to consider that you can you can push a 12"+ balloon with a three foot paper streamer though a prop and come out the other side without cutting something :rolleyes: but AirBoss Bob says he still isn't giving points for nothing but prop pops and streamers :--)

It was a blast ? See you back on the Mountain! :)

Bill

PS The rules were ?. fly the racetrack at 1600, 130MPH, initial 300 AGL over the numbers, and call for release,...do what you want but hit it in a climb, 1 point for a streamer and 4 points for a kill....thinking nothing but prop!

PPS ?. Don Winters was the deadeye dude of the day and he paid back right at 14 to 1 odds. I had $5 on his prop and got $70 back.... woo hoo! :D

PPPS ?. quick credit to Marvin Homsley for thinking we could do it and helping with the testing ?. which did not help him with the prop popping :)

Still not sure how the guy I bet on came in last, but still made money on the betting.....
 
Ah, Calculus! Alas, it has been so long since I've burned the midnight oil enjoying your endless delights! ;)

I once woke up in the middle of the night, shouting, "d-y...d-x!" And then went back to sleep.

My wife thought I was nuts!!!

Hey, I once woke up at 3 a.m. and got out of bed, leaving a gorgeous blonde in it, while I went to the desk and wrote down the solution to an ODE that had been gnawing at me for a few days.

She thought I was nuts, too, and in retrospect, I certainly was. :)
 
While we are on the subject of calculus.... I think the cross-section of the balloon should be integrated over the change in volume, not area :) it is a variable size in all three dimensions. It's been WAY too long since I flunked out of that class, but I'm sure someone wants to crank it out!

I'm looking forward to the rematch next year. Do you have a plan for breaking a tie, Bill?

Don

PS - I printed up a ballcap mount for my camera. Maybe I'll catch one of these balloons passing through the prop disc unscathed....

ovP.jpg
 
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:)

I think Bob said something about Horton Confetti but he is a gracious AirBoss :)

Ok so next year ?. 2 foot balloons. ;) We found a source for large amounts of helium.

Hmmm, maybe 2 extra points for clogging up the fins on the front cylinders, and 3 extra points for blocking the induction inlet? :p
 
Or tie a loop in the streamer and see who can bring the balloon back in tact!

No abnormal temps on the way home Sunday, but the thought of a plugged oil cooler did cross my mind.
 
Hmmm, how do I fit a balloon popping laser into the spinner . . .
 
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LASERS available

Hmmm, how do I fit a balloon popping laser into the spinner . . .

Ben, funny you should ask. Coincidentally, we have a balloon popping laser that you can rent at the registration desk. ;) It is designed to mount on the glareshield and shoot through the prop arc because apparently that is where all the balloons somehow happen to go through without breaking. The ONLY downside is that it is manually operated and does cut aluminum really well .....

..... but hey, it's not my airplane :D
 
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